Tray stacking machine



Dec. 1, 1953 w. G. TRIGWELL 2,561,102

TRAY sTAcKING MACHINE med Aug. 5o, 194s 9 Sheets-sheet 1 INVENTOR wm. G'. Trgwell ATTORNEYS 9 Sheets-Sheet 2 Filed Aug. 3G, 1948 xx Kaka@ wel m. uw W INVENTOR Nm mm uw@ i@ ATTORNEYS Dec. l, 1953 W. G. TRIGWELL TRAY STACKING MACHINE 9 Sheets-Sheet 5 Filed Aug. 50, 1948 R u s O 6 Y T E m w m wm ww NN m /U Tr A G NW O w {III (Illu Y vm. l a mm 'Il mv Qw\ \-m mv mw\ mm Nw L I \\mmw W. G. TRIGWE LL TRAY STACKING MACHINE Dec. 1, 1953 9 Sheets-Sheet 4 Filed Aug. 30, 1948 n. l. R

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ATTORNEYS Dec. l, 1953 w. G. TRIGWELL 2,661,102

TRAY STACKING MACHINE 'filed Aug. 5o, 1948 9 sheets-Sheet 5 O FU '0 u m f@ 9 f6 f@ 9 9 N fo g O v; U

. "l lNvENToR lvm. G'. TrzlgweLL BY wim/LLL ATTORNEYS Dec. 1, 1953 w. G. TRIGWELL.

TRAY sTAcxING MACHINE 9 Sheets-Sheet 6 Filed Aug. 30. 1948 INVENTOR wm. G Trzlgwcl @is Dec. l, 1953 w. G. TRIGWELL 2,661,102

TRAY sTAcKING MACHINE Filed Aug. 30, 1948 9 Sheets-Sheet 7 \\\\\\\\\\\\\\\\\& INVENToR s1 BY-MWL ATTORNEYS Dec. 1, 1953 w. G. TRIGWELL 2,661,102

TRAY sTAcxING MACHINE Filed Aug. 5G, 1948 9 Sheets-Sheet 8 27kg'. I2

NVENTOR. wm. G. Trigwell mimi? Dec. 1, 1953 w. G. TRIGWELL 2,661,102

TRAY sTAcjKING MACHINE Filed Aug. 50, 1948 9 Sheets-Sheet 9 f-Q $5 q Eg' J6 I 86 a5 a4 as Il W um jf 8l ,/82

a2 2f /aa INVENTOR wm. G. Trzlgwel Z BY MM ATTORNEYS Patented Dec. 1, 1953 UNITED STATES PATENT OFFICE TRAY STACKING MACHINE William G. Trigwell, Capitola, Calif., assigner to Chapman Dehydrator Co., Inc., Modesto, Calif., a corporation of California Application August 30, 1948, Serial No. 46,865

7 Claims.

This invention is directed to, and it is an object to provide, a novel machine for automatically stacking fruit or vegetable dehydrator trays on cars preparatory to movement through the dehydrator.

Another object of this invention is to provide a tray stacking machine which is operative to deliver trays, from an endless conveyor, into stacked relation on a car in predetermined position in the machine; the car being automatically lowered step by step as the trays stack onto said car whereby the novel feeding mechanism of the machine functions, at all times, in the same horizontal plane, as is desirable.

A further object of the invention is to provide a tray stacking machine, as in the preceding paragraph, wherein said feeding mechanism acts to successively feed the trays from the conveyor onto a receiving frame over the car; such feeding mechanism being controlled by the passage of the .trays on the conveyor, and in turn release of trays from the receiving frame, for dropping therefrom and stacking on the car, is responsive to actuation of said feeding mechamsm.

An additional object of the invention is to provide a tray stacking machine wherein novel car lowering apparatus is included to accomplish the aforesaid step by step lowering of the car to compensate for increase in the height of a stack of trays on the car.

It is also an object of this invention to provide a tray stacking machine having a car lowering apparatus, as in the preceding'paragraph, which includes an elevator, and a novel switching system for the electric motor drive assembly which is associated with such elevator; such switching system being automatically responsive to a tray fed onto the receiving frame, whereby to then cause the drive assembly to effect a corresponding lowering step of the elevator and supported car.

Another object of the instant invention is to provide a tray stacking machine which functions smoothly and positively to stack dehydrator trays on a car; the machine, while in the main automatic, being designed so that the cycle of the 'A ymachine remains proper even though the trays feed from the endless conveyor with uneven spacing or timing therebetween. l A further object of the invention 1s to produc a practical and reliable tray stacking machine,

and one which will be exceedingly effective for y the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specication and claims.

In the drawings:

Fig. 1 is a plan view of the tray stacking machine.

Fig. 2 is a side elevation of the machine.

Fig. 3 is an enlarged fragmentary plan view of one tray feeding mechanism with the parts in the positions occupied thereby upon approach of a tray to the end of the conveyor, but before the start of the feeding operation.

Fig. 4 is a similar view but shows the feeding mechanism in operation; the tray having been fed from the conveyor onto the tray receiving frame.

Fig. 5 is a cross section on line 5 5 of Fig. 4.

Fig. 6 is an enlarged fragmentary sectional elevation of said one feeding mechanism at the start of a tray feeding operation.

Fig. 7 is a similar view but shows said feeding mechanism at the end of a tray feeding operation.

Fig. 8 is an enlarged fragmentary plan view of one end portion of the tray receiving frame, showing the corresponding tray supporting ledge advanced.

Fig. 9 is a similar view but shows the ledge retracted.

Fig. 10 is a cross section on line Ill-l0 of Fig. 3.

Fig. ll is a cross section on line iI--H of Fig. 9.

Fig. 12 is a fragmentary plan view of the tray receiving frame at the end opposite the endless conveyor, and shows the tray actuated switch unit which controls the step by step lowering motion of the elevator and car thereon.

Fig. 13 is a cross section on line l3|3 of Fig. 12.

Fig. 14 is a cross section on line ill-M of Fig. l2.

Fig. l5 is a fragmentary elevation of the actuating mechanism for the switch which controls upward motion of the elevator; said mechanism being in its normal position with the switch open.

Fig. 16 is a similar view but shows said mechanisrn in an operative position with the switch closed,

Fig. 17 is a diagrammatic representation of a reversing circuit for the motor; said circuit including the downward motion and upward motion control switches for the elevator.

Referring now more particularly to the characters of reference on the drawings, the tray stacking machine comprises an upstanding main frame I of open construction, which includes vertical corner posts 2; said main frame I being disposed in, and projecting above, a pit 3. The pit 3 is of substantial depth below the floor level 4, and both said pit and the upstanding main frame I are elongated transversely of a rail line which intersects the pit intermediate its ends.

The rail line includes rails 5 mounted on the iloor on opposite sides of the pit and separate but matching rails 6 on a rectangular elevator l mounted in connection with the Ina-in frame l for vertical travel. The elevator. 'l is generally symmetrical to the frame I in plan and` includes sleeves which run on the corner posts 2 whereby, to guide said elevator.

The elevator I is adapted to be moved vertically within the opstanding main frame l by the` following electric motorI driven assembly: 4

The numeral S. indicates.. a reversible. electric mutui' mounted herum-iene, uuu uf the unsteading main frame lbelow the top oi the latter; such reversible electric 'motor Q driving across Shaft l0. through the medium uf. searing IL, At opposite ends, and in alinement with correspondins eed nests the @russ .Shaft lil. 1S fitted.' with cable drums l2. I

A. Cble. 1.3 S WOW@ @9911i am'CXtelldS UQWH'C 1r from @ach @151.11.11 i2. and casses @ver a direstiouchausiue Sheen 'I4 un' the culresruuuius @o1-ner post 2 adjacent its unser eau. Floru each direction-changing sheave I4, the corresponding cable I3 is reeved in hoist relation to the elevaiur i br maus iuuluuuig direction-Charging sheaves l5, It, and Il, with each cable anchored to the elevator at opposite ends, as at I8 and I9. When electric motor e is run in one direction, the cables I3 unwind from'the drums I2 to lower the elevator while reverse travel of said motor and drums Winds the @able Qu the Same and 12.15% @he elevato? When the elevator i is disposed at floor level 4, the rails Q on said elevator' aline with the rails 5 QU. thi? 300%? Wleeby i dehydmiq' 99d' 2te can loe movedonto the elevator; there being a releasable, car locating stop device 2| on Vone side of the elevator. In Fie.4 1 the car is shown to one side'oicv the ktray stacking machine, while in Fig. 2, said car is shown resting on theelevator.

After a car 2E is run onto the elevator l, and located in position, the elevator is raised to a starting position, as in full lines in Fig. 2.

Above the horizontal plane of the car 20, when the elevator l is in such raised starting position, the machine includes a tray receiving frame, indicated generally at 22, which is elongated lengthwise of the machine; such frame being of generally U-shape, open at what may be ter-med the inner end of the machine, and closed at the outer end of the machine. The tray receiving frame 22- includes rigid side bars 23 and a rigid cross bar 24.

At its outer end the tray receiving frame 22 is journaled by bearings 25 to a cross shaft 25 which extends horizontally between the corresponding corner posts 2. Arms 2l project outwardly from the outer end of the frame 22 and carry a counter-balance weight 28 whereby to facilitate swingingof the said tray receiving frame 22 from a normally horizontal position upwardly to an out-of-the-way position.

.An endless longitudinal conveyor 3| is mounted on the floor 4 and extends lengthwise to a point closely adjacent the inner endof',` and in feeding alinement with, the tray receiving frame 22;

such conveyor 3l being adapted to feed dehydrator trays in a row, in spaced relation, toward the tray receiving frame 22.

rI'he conveyor 3| includes a pair of transversely spaced, endless conveyor chains 32 which carry trai/.1 adi/euries Cleats 13.3: Such Chains 32 being trained about driven sprockets .24 at the end of the conveyor adjacent the tray receiving frame 22. The sprockets 34 are secured on a cross shaft 35 driven, intermediate its ends, as at S.

each tray .'il is fed off the discharge end OI the conveyor 3l, such tray is disposed mainly on the tray receiving frame 22, except for a trailing end portion of said tray. It is thus necessary to provide for supplementary feeding to iurther advance the tray to its full-on position on the frame 22, wherein the outer end of the tray abuts vstops 38 on the rigid cross member 24. The -trarne 22L includes, in cooperation with the rigid side bars 23, longitudinal ledges 39 `which are normally advanced inwardly to a partially exposed position to receive and support the tray.

pair of supplementary tray feeding mechanisms, each indicated generally at 40, are embodiedl in the machine at the discharge end of the conveyor 3 I' said mechanisms being disposed laterally outwardly of corresponding sprockets 34 and driven by adjacent ends of the cross shaft 2 5. As Vsuch supplementary tray feedingmechanisms 4o arer identical structure and function, a description or one will sumce for both:

Laterally outwardly of the corresponding sprocket 34, the driven cross shaft 35 is tted with a disc 4I which car-ries an l shaped dog 42 in pivotally mounted relation eccentric to the dise` axis; the dog being pivoted, intermediate its ends, to thedisc, as at 43. With each revolution of the disc 4I in the direction indicated by the arrow in Figs. 6 and 7, the pivotally mounted dog -42 hangs free except at the top. and forward quarter'or` each revolution; there being a stop pin 44 positioned to-prevent undue inward swinging of said dog.

As the pivot 43 of the dog 42 moves slightly ahead oftop dead-centerposition, as in Fig. 6, the foot 45 'ci said dog 42 rides onto. a cam 46 generated in a design adapted to cause the dog -42 vto swing to a position projecting outwardly from the disc 4I. With continued travel of` said disc 4I, the dog 42 swings forwardly and .downwardly, as in Fig. 7:, engaging the trailing end 41 of a tray on the receiving frame 22, whereby to advance saidtray to its full-on position on `such frame, and against the. stops 38.

LThe cam 46 is normally in the path of travel of the dog 42, being mounted on a lateral extension 48 of a transverse arm 49 which extends `in axial-ly slidable, but non-rotatable, relation through a guide 50 secured in connection with theA bottom or a side bar 5I which extends along the adjacent side or the. conveyor- `3 I..

It is desired that the cam 46 beA shitted laterally, out of the path of the dog 42, whereby the latter Willbe inoperative andy not project, when a tray is passing' over the disc 4I, as otherwise the dog would project 4and dislocate the tray.

'The aforesaid shifting of the ca rn to an outoftheway position'isaccprnplished as follows: a pairof longitudinally spaced, vertical spindles -52 are Journaled outwardly of the side barA 5I,

and at their lower ends said spindles 52 include generally radial levers 53 which extend forward-ly and inwardly topivotal connection with a longitudmal bar 54, which bar slidably engages V.through the arm 49 adjacent its free end. At

55 are fitted with vertical rollers 56.

As a tray 31, traveling on the conveyor 3l, approaches its discharge end, the rollers 56 are engaged by the tray and thrust laterally outwardly, as in Fig. 3, rotating the vertical spindles 52 to such extent that the radial levers 53 swing in a direction to move the longitudinal bar 54 laterally outwardly along with the arm 49 and the cam 46 carried thereby. Thus, as a tray sweeps over the discharge end of the conveyor 3l, the dog 42 swings freely about its pivot 43, traversing a path below the tray.

This condition prevails until the tray is discharged from the conveyor 3l, at which time the tray has fully escaped the rollers 56 so that the dog 42, as it next travels through the upper and forward quarter revolution, is cam-actuated to accomplish the aforesaid supplementary advance of the tray 31 by engaging its trailing end 41 in the manner previously explained. As soon as a tray discharges from the conveyor 3l and escapes the rollers 56, a tension spring 51, connected to an extension of one of the radial levers 53, causes said levers to swing in a direction to advance the arm 49 laterally inwardly to place the cam 46 in its operative or dog engaging position.

Each tray 31, when in full-on position on the tray receiving frame 22, is supported by the normally laterally inwardly advanced ledges 39, which ledges are mounted and function as follows:

The ledges 39 are flat longitudinal plates engaged in laterally slidable relation in grooves 59 in the rigid side bars 23; there being a longitudinal row of spaced parallel links 59 connected Y between each ledge 39, through a cut-out in the top flange 60 of the corresponding side bar 23, and a boss 6| at the rear of said side bar. The parallel links 59 of each row are disposed at a forward and inward inclination so that upon longitudinal shifting of the corresponding ledge 39 in a direction away from the conveyor 3l, said ledges automatically retract full into the groove 48; dropping the previously supported tray onto the car 20 disposed symmetrically below the tray receiving frame 22.

Such longitudinal shifting of the ledges 39, to retract the same and cause the dropping of a supported tray, is accomplished by mechanism actuated by the dogs 42 after the same Ihave effected the supplementary feeding of said tray but before such dogs escape the corresponding cams 46. Such mechanism comprises the following:

Directly ahead of the discharge end of the conveyor 3| there is a cross shaft 62 journaled in connection with the side bars I and having upstanding radial levers 63 in the path of the dogs 42 when the latter are cam projected; said levers 63 including outer end rollers 63a.

When the dogs 42 complete the supplementary feeding action of a tray 31 and escape the trailing end of said tray, said dogs--as they continue downward travelengage and swing the levers 63 forwardly. When this occurs there is a corresponding forward swinging motion of other upstanding radial levers 64 on opposite ends of the cross shaft 62; the levers 64 having rollers 65 on their upper ends which bear against lugs 66 on ledges 39. When the rollers 65 swing forwardly against the lugs 66, there is a corresponding longitudinal shifting movement of the ledges 39 and automatic retraction thereof to drop the supported tray onto the car 29. As soon as the dogs 42 escape the radial levers 63, the same assume their starting position, by reason of the fact that the ledges are longitudinally rearwardly urged by means of tension springs 61 connected to certain ones of the parallel links 59.

As each tray 31 is fed onto the tray receiving frame 22, it causes the reversible electric motor 9 to be energized to run in a direction to lower the elevator 1 one step, corresponding generally to the thickness of the tray, and which tray drops onto the car 20, in the manner previously described. This result is accomplished as follows:

At the outer end of the tray receiving frame 22, and disposed in one corner thereof, is a tray actuated switch unit, indicated generally at 68. rIhis switch unit comprises a web-like arm 69 pivoted on the corresponding side bar 23 at the top, as at 10, and normally projecting laterally inwardly therefrom. The web-like arm 69 is urged, by a tension spring 1I, in a direction contra to movement of the trays onto the frame 22. At its laterally inner end the web-like arm 69 includes a vertical pin 12 of substantial height disposed in the path of the outer end of a tray moving on the frame 22 and approaching, but short of, the stops 38. The vertical pin 12 projects downwardly to a termination in a .horizontal plane somewhat below the bottom of a tray on the frame 22 (see Fig. 13).

A horizontal cam 13 projects forwardly from the web-like arm 69 for engagement with a roller 14 on the outer end of a plunger 15 of a normally spring-opened switch 16. Upon forward swinging motion of the web-like arm E9, the cam 13 engages and advances the roller 14 and plunger 15, closing the switch 16. Further, the cam, as long as the arm 69 is swung forwardly, holds the roller 14 and plunger 15 in a switch closing position.

The normally spring-opened switch 16 is interposed in a reversing circuit 11 connected to the electric motor 9; such switch 16 being inthe side of the circuit 11 which causes the electric motor 9 to run in an elevator lowering direction.

Thus, as each tray is fecl onto the tray receiving frame 22, the outer end of such tray engages the pin 12 and causes closing 0f the switch 16 during the final motion of the tray onto said frame 12; the cam 13 holding the switch 16 closed as long as the tray remains on the frame 22, which is only a few moments because the ledges 39 almost immediately retract to drop the tray onto the car 20. While the tray remains full on the frame 22, the switch 16 is closed, and the reversible electric motor 9 runs in a direction to effect downward lowering of the elevator 1 and car 29. Immediately upon the tray 31 being released by retraction of the ledges 39 to drop onto the car 26, said tray escapes the pin 12, and the spring 1I swings the web-like arm 69 rearwardly with respect to the roller 14, whereupon the switch 16 automatically opens, stopping the electric motor 9. In this manner there is an automatic step-by-step downward lowering of the elevator 1 and car 29 thereon with successive feeding of trays 31 onto the tray receiving frame 22. Consequently, as the stack of trays on the car 20 increases in height, the car is automaticalcomplete, at vwhich time the zelevator and -car will b'e Aadjacent the lbottom fof the pit -3.

After a stack of trays is'oompleted on the elevater supported car `2|), the endless iconveyor 3| -is stopped, andthe following switching arrangement is brought into :play to raise 4the elevator :tromwithin the pit Yiirst fto Jfloor level Yfor removal of the loaded Vcar and placementof an unloaded car; the frame 22 Vbeing swung upwardly to an out-of-the-way position ibeore 1the loaded car is raised, so that Lthe `stack of trays thereon -does not strike said frame. After lsuch removal fof lthe lloaded car Ifrom the elevator, A(and placement of an unloaded Vcar thereon, :the frame A22 :is swung downwardly kto its normal horizontal Ipo- `-sition and thereafter the elevator `is raised :to its starting position closely adjacent the tray refceiving :frame 22.

The aforesaid switching arrangement, by means of which the above lis accomplished-comprises a pair Yof vertically spaced, `snap-action .levers 18 and 19 which are .pivoted at -80 and 8|, respectively, to 'a vertical frame 82 'which 4upstands in adjacent parallel relation to one of the 'corner ,posts 2 at the inner end or the machine. The snap action :levers 18 and 19 project toward but extend alongside `the 'adjacent coi-ner post 2 and are disposed in the ,path-of a `laterally outwardly projecting pin 83 on the relevator sleeve 8 which runs on said corner post2.

A manually actuated control rod 4, vincluding a top hand knob f85, projects "through the top of the verticalirame 82; there being spaced stop collars 86 which limit the throw of said rod *84.

VAt its lower Send the lcontrol :rod 84 yis l.pivotally connected, .as at 81, V'to the upper snap Yaction lever 19 intermediate :its ends.

A connecting rrod unit 88 .pivotally Vconnects between 'the upper and lower -s'nap action levers 18 and 19 intermediate the ends rof .the latter, and said unit includes `a Vspring assembly -89 which permits "of upward yielding of 4the flower snap action .lever 18 independently for lthe upper snap action lever 19, but normally tends to maintain said snap action .leverstparalleL The lnormal"position of the snap aotionievers A18 and 19 is raisedfas in-Fig.'l5, and "a 'mercury 'type vcontact switch 'i90 is mounted 'on the lsnap action lever 19, being 'open when `said lever is raised. The switch'90 is interposed in 'the reversing circuit 1T on the side opposite 'the-elevator lowering control `switch 1B, and comprises the elevator raising control switch. AIn Vother words when the'normally open switch 90 is closed, the electric motor v9 is energizedtorun in a direction to raise the "elevator 1.

With the elevator 1 in the bottom oi the pit and supportinga stack loaded car29, thepperator thrusts 'the control rod 8l! downwardly, `which swings the lever 19 to its full-line .position vaof Fig. V16 and the lever'l to its dotted-line position of said gure. VWhen 'this occurs switch @il closes, and the motor 9 'rasesthe elevator V1.V `When said elevator're'aehes the iloo'r level 4, 'pin 83 strikes the snap action Vlever 18 -andurgeslit upwardly,along with the .control ro'dun-it'fand the snap actionlever 19, whereupon the switch 90 is opened and themotor 9 stops. .lhe -loaded car is then run 'from the elevator rails Aii ontothe iloor rails 5, and an unloaded car .is placed on the elevator. Then the operator --again .thrusts the control rod-=84 downwardly to close the switch rElli, whereupon the motorwagain-raises the elevator. which motion continues until the pin83 yengages and actuates the .lever '19 toits 'normal switch opening position, las lin :fulllines in Fig. l5. Upon this occurrence, the switch opens and .the motor r'stops, with .the :elevator at its :raised or starting position. The -pin `83, -upon such -further raising of the elevator, may pass by the lever 18, for -t-he .reason that the latter -is upwardly yieldable through the medi-um of the spring assembly 89.

With the ydescribedswitching arrangement, the 'operator has full 'con-trol -of initiating -the raising motion `of the elevator, ,fboth from within the pit `and f-at iloor level, 'buts'topping yof said 'elevator `at floor level, 'and :at its initial starting .position lthereabove, -is automatic.

When the elevatoi` '1, with an unloaded c9120 thereon, is returned -ito I'the elevated, :initial l"starting position, the conveyor .3| is again placed in operation, whereupon the cycle-of stacking trays 'onthe 'car is-repeated.

'The vdescribed tray Vstacking machine is so varranged that the vsequence of its operations fis smooth and welltime'd, yet without requiring-any predetermined spacing of the trays Uon the con-- veyor 3i. The machine operates smoothly and reliably for the intended purpose, and is `so designed that it requires a minimum of maintenance or repair.

From the 'foregoing descriptionfit will be'readily seen that Ithere has been 'produced such amachine as substantially fulillls the objects of .the invention, as set 'forth herein.

Wh-ile thisspecica'tion sets -forthin detail the present and preferrediconstruction of 4the machine, still in practice such deviations from such detail may be resorted to as do not form a departure -fi'om the spirit of ythe invention, as defined bythe appended claims.

Having thusrdescribed the invention, 'the -following `is 'claimed as Inew .and useful, and upon which Letters Patentare-desired:

1. A tray. stacking machine comprising 4`a tray conveyor, van open frame mounted beyond .the discharge end 'of the econveyorfor the reception of trays one sata time from the rconveyor an'd to then support each tray-in :a predetermined po"s`i tion, .the .frame vincluding normally laterally fin- `wardly yadvanced but laterally outwardly retractable ledges on opposite sides thereof which enga-ge in 4supporting relation below each tray in said position, la stack support below the l'frame "disposed -tocatch 'dropped trays in a stack thereon, the ledges being loi'igi'tudinal members :slid'a-ble -insaid direction, meansconnected to the ledges to cause the same to retract'and release a supported tray upon longitudinal sliding of the ledges, and means to effect said longitudinal slidingV of the ledges in timed relation to reception of a tra'y ,on-the frame in said predeterniined position; there being a supplementary feeding mechanism mounted to a'dvance conveyor discharged trays onto the frame and to 'said `predetermined position, 'andysaid means which eifec'ts longitudinali Jsin-ing ofthe iedges being actuated .by said mechanism.

.2. A tra'y 'stacking machine comprisingan endless conv'eyona vframe disposed beyond the. discharge end of the conveyor adapted to releasably receive conveyordischarged trays for stacking,

Aand a supplementary, tray feedingmechanism vmounted to'act on conveyor 'discharged traysto .advance-the same'toa, predeterminedpo'sition on the frame beyond any point of advance by said conveyor; said supplementary, tray feeding mechanism including a driven cross shaft adjacent the discharge end of the conveyor, and a rotary unit on the cross shaft including a member adapted, upon rotation of said unit, to project and engage each conveyor discharged tray at the rear end to impart supplemental forward motion to said tray; the frame including normally projected but retractible ledges which receive each tray, and means actuated by said supplementary feeding mechanism, after advancing each tray, operative to then retract the ledges so that such tray drops from the frame for stacking.

3. A tray stacking machine comprising an endless conveyor, a frame disposed beyond the discharge end of the conveyor adapted to releasably receive conveyor discharged trays for stacking, and a supplementary, tray feeding mechanism mounted to act on conveyor discharged trays to advance the same to a predetermined position on the frame beyond any point of advance by said conveyor; said supplementary, tray feeding mechanism including a driven cross shaft adjacent the discharge end of the conveyor, a rotary unit on the cross shaft including a member adapted, upon rotation of said unit, to project and engage each conveyor discharged tray at the rear end to impart supplemental forward motion to said tray, and mechanism actuated ,by a tray passing over the rotary unit to place the member out of operation until the tray reaches a position clear of the unit.

4. A tray stacking machine comprising an endless conveyor, a frame disposed beyond the discharge end of the conveyor adapted to releasably receive conveyor discharged trays for stacking, and a supplementary, tray feeding mechanism mounted to act on conveyor discharged trays to advance the same to a predetermined position on the frame beyond any point of advance by said conveyor; said supplementary, tray feeding mechanism including a driven cross shaft adjacent the discharge end of the conveyor, a rotary member mounted on the driven cross shaft, a dog pivoted on the rotary member for projecting beyond the periphery thereof, a cam mounted in position to engage the foot of the dog and cause said projection of the latter through a predetermined portion of each revolution, whereby the dog then engages a corresponding conveyor discharged tray at the rear end to impart supplemental forward motion to said tray; the cam being mounted for shifting motion out of -the path of the foot of the dog, and mechanism actuated by a tray passing over the rotary member and dog operative to so shift the cam and place the dog out of operation until the tray reaches substantially the point of discharge from the conveyor.

5. A tray stacker comprising in combination with a stack receiving instrumentality, a rigid frame disposed above said instrumentality, a. pair of laterally spaced apart ledges to support a tray mounted on opposite sides of said frame for movement between a normal tray supporting position and a non-supporting position, the ledges normally projecting inward of said sides, conveying means for advancing a tray onto said ledges to a predetermined position when the ledges are in such normal position, means to move the ledges to said non-supporting position after the tray is so positioned on the ledges, the conveying means including a driven endless conveyor operative to push a tray to a rst position part way onto the ledges, and other driven means operative to then push the tray -to such predetermined position; such other means including a shaft connected in driving relation with the endless conveyor, discs xed to the shaft, L-shaped dogs pivotally mounted on the faces of the discs at poin-ts eccentrically of the central axes of the discs, and cams xed at points separate from the discs and `eiiective upon rotation of the discs to engage one leg of the L-shaped dogs and swing the other legs into contact with the end of the tray as it stands in said first position and complete its movement to said predetermined position.

6. A stacker as in Iclaim 5 in which the means for sliding the ledges includes a lever means mounted at points between the discs and the adjacent ends of the ledges and engaging the latter, the dogs engaging and operating said lever means to slide said ledges in a diagonal direction after the dogs have moved the tray to said predetermined position, links pivoted at one end to the frame at points laterally out from the ledges and such links being normally yieldably held in a position .transversely of the ledges, the other ends of the links being pivoted to the ledges.

7. A stacker as in claim 6 in which the lever means includes a shaft, one lpair of lever arms fixed to the shaft and ,being engageable by the said legs of the dogs, and another pair of lever arms xed to the shaft and having their free ends engageable with the ledges.

WILLIAM G. TRIGWELL.

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